An Operational Rapid Intensification Prediction Aid (RIPA) for the western North Pacific

This study describes an operational, since September 2017, Rapid Intensification Prediction Aid (RIPA) developed specifically for JTWC operations for use in the western North Pacific. The RIPA makes probabilistic and deterministic forecasts for the 24, 36 and 48h lead times. Specifically, it uses the intensity change thresholds or RI thresholds of 25-, 30-, 35-, 40-knot (kt) changes in 24 hours, 45- and 55-kt changes in 36 hours, and 70-kt changes in 48 hours. Predictors used for making probabilistic forecasts are readily available in the routine diagnostic files produced by JTWC’s version of the Statistical Hurricane Intensity Prediction Scheme (SHIPS) model. Many of the predictors are identical to those used in RI prediction in the Atlantic and eastern North Pacific Probabilities, but not all. We also treat recent intensity trends in a different manner. Probabilistic forecast models use two methods, namely linear discriminant analysis and logistic regression. The forecasts of these two methods create an equally weighted consensus probability for each RI threshold. When the consensus probability exceeds 40%, RIPA generates a deterministic forecast for that RI threshold. Finally, the largest intensification rate for each forecast lead-time becomes a member in the operational intensity consensus; nudging the consensus in the correct direction.

In this presentation, we will present discuss the details of RIPA forecast model components along with independent forecast verification of both the probabilistic forecast models for each RI threshold and the deterministic RI-nudged intensity consensus.

Disclaimer: The views, opinions, and findings contained in this report are those of the authors and should not be construed as an official National Oceanic and Atmospheric Administration or U.S. Government position, policy, or decision.